[extension/opamp] Implement ReportsHealth capability

[bondyr]

Component(s)

extension/opamp

Describe the issue you're reporting

The documentation states that opamp extension should support 3 capabilities:

The opamp extension implements an OpAMP client with a small subset of OpAMP agent capabilities:

• ReportsStatus
• ReportsEffectiveConfig
• ReportsHealth. The extension reports Collector's health on startup and any time the health changes. In order to do this the opamp extension needs access to the health of the Collector. [...]

In opamp extention source code, ReportsHealth is not currently implemented. Unless left out deliberately, please consider prioritizing it so that opamp extension would support all 3 basic capabilities.

[github-actions]

Pinging code owners:

• extension/opamp: @portertech @evan-bradley @tigrannajaryan @BinaryFissionGames

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[bacherfl]

I would be interested in implementing this

[bacherfl]

The PR implementing this should now be ready for review